Key Takeaways: Why Your Highlander Won't Start
- The Sequence Matters: You must press Lock, Lock, and then HOLD the Lock button for 3 seconds. Timing is everything.
- Subscription Status: On the 2021 Highlander, key fob remote start is linked to the Remote Connect subscription. If your trial expired, the fob might stop working.
- Safety Locks: If the hood is unlatched, a door is open, or the "Check Engine" light is on, the system disables remote start.
- Battery Health: A weak key fob battery (CR2032) or a weak 12V car battery will prevent the signal from going through.
- Sleep Mode: If you haven't driven the car in a week, the remote receiver turns off to save power.
The First Thing to Check: Your "Lock-Lock-Hold" Timing
If you're standing in the driveway freezing and the car isn't starting, let's fix the technique first before we worry about broken parts. The 2021 Highlander is picky about how you ask it to start.
Most people press the buttons too fast. Here is the exact rhythm you need:
- Press LOCK (wait 1 second).
- Press LOCK again (wait 1 second).
- Press and HOLD LOCK for 3 seconds.
You have to hold that last press until the hazard lights on the mirrors flash. If they don't flash, the car didn't get the command. Its actually pretty common to let go too early. Count "one Mississippi, two Mississippi, three Mississippi" while holding it.
If the lights flash but the engine doesn't crank, then we have a different problem. But if the lights never flash, it's usually the fob signal or the subscription issue.
The Big Issue: The Subscription Confusion
Okay, we need to talk about the elephant in the room. This is where alot of 2021 Highlander owners get frustrated. There was a huge controversy a while back about Toyota linking the remote start function on the physical key fob to a paid digital subscription.
According to reports from The Drive and other auto news outlets, the functionality of your key fob is tied to the Remote Connect service.
Which Audio Package Do You Have?
Your 2021 Highlander likely came with one of two audio setups, and this dictates your trial period:
- Audio Plus: This usually came with a 3-year trial of Remote Connect. Since we are past that 3-year mark from 2021, your trial has likely expired.
- Premium Audio: This often came with a 10-year trial. If you have this, your subscription should still be active.
If you have Audio Plus and never renewed the subscription (which costs about $8 a month or $80 a year), Toyota may have disabled the remote start capability on your fob. I know, it sounds crazy that a radio signal from a key needs a subscription, but thats how the software was set up for these model years.
The Fix: Download the Toyota app on your phone. Log in and check your subscription status. If "Remote Connect" is expired, try renewing it for a month. If the remote start suddenly works again, there is your answer.
Safety Interlocks: The Car is Protecting Itself
If your subscription is active and your fob battery is good, the car might be refusing to start because it thinks it's unsafe to do so. The computer checks a bunch of sensors before it gives the green light to the engine.
Here are the most common reasons the computer says "No":
1. The Hood Latch Sensor
This is a big one. There is a small switch under the hood that tells the car if the hood is closed. If this switch is broken, dirty, or just slightly misaligned, the car thinks the hood is open. The car will absolutely not remote start if it thinks the hood is up because it doesn't want to blend a mechanic's hand in the engine fan.
Check this: Pop your hood and slam it shut firmly. If you see a warning on your dashboard that the hood is open when it's actually closed, you have a bad sensor.
2. Doors and Hatch
Similarly, if a door isn't closed all the way, or the rear liftgate is slightly popped, it won't start. Walk around the car and push on all the doors. Sometimes the kids don't close them hard enough.
3. The "Check Engine" Light
If you have a Check Engine Light (CEL) on your dashboard, remote start is automatically disabled. This is a safety feature. The car doesn't want to run without a driver present if there is a potential engine problem. Even a minor issue, like a loose gas cap that triggered the light, will kill the remote start function.
The Fix: You need to scan the code and clear it. Once the light is off, remote start should work again.
4. Low Fuel
If your gas light is on, the Highlander won't remote start. It's smart enough to know that idling for 10 minutes might run the tank dry, leaving you stranded. Fill up the tank and try again.
Key Fob Battery Issues
Even if the little red light on your key fob lights up, the battery might still be too weak to send the strong "long distance" signal needed for remote start. Locking the doors takes a quick pulse of energy. The remote start sequence requires a sustained signal.
If you haven't changed the battery in your 2021 fob yet, do it now. It's been a few years, and they usually last about 2-3 years.
How to change it:
You don't need a mechanic for this. You just need a CR2032 battery. You can get them at any grocery store.
- Pull the mechanical emergency key out of the fob (slide the little switch on the side).
- Stick the tip of that key into the slot and twist to pop the plastic case open.
- Remove the circuit board gently (don't get it wet!).
- Swap the battery. Make sure the + side is facing up.
- Snap it back together.
Sometimes the metal contacts inside the fob get a little flattened out. If a new battery doesn't help, try bending the little metal prongs up slightly so they make better contact with the battery.
The "Sleep Mode" Factor
Toyota has a battery-saving feature that confuses a lot of people. If you haven't driven your Highlander in a week or more (some manuals say 9 days, others say 14), the remote start receiver shuts down.
It does this to stop the constant searching for a signal from draining your main 12V car battery. If you've been on vacation and try to remote start the car at the airport, it might not work.
The Fix: You have to unlock the car manually with the fob button or the door handle. Once you open the door, the system "wakes up," and remote start will work next time.
Is There a Spare Key Inside?
The 2021 Highlander is designed to prevent theft. If the car detects another smart key inside the cabin, it might disable remote start. This happens alot if you have a spare key hidden in the glove box, or if your spouse left their purse/bag in the car with their key in it.
The car gets confused. It thinks, "Why are you trying to remote start me if the key is already inside? Just push the button on the dash!" Locate all your keys and make sure they are outside the vehicle.
Troubleshooting the Toyota App
If you are using the phone app instead of the key fob and it's failing, that's usually a server issue, not a car issue.
The Toyota app is... well, it's not known for being the most stable app in the world. If the app says "Request Failed," try these steps:
- Update the App: Go to the App Store or Google Play and make sure you have the latest version.
- Relogin: Sign out and sign back in. It forces the app to refresh the data from the server.
- Check Signal: Remember, the app talks to the cloud, and the cloud talks to your car via cellular data (AT&T usually). If your car is parked in a deep underground garage with zero cell service, the app can't reach it. The key fob might still work, but the app won't.
The "Valet Mode" Check
While less common on the newer models, some security settings act like a Valet Mode. Dig through your infotainment screen. Go to Menu > Vehicle > Vehicle Customization.
Look through the door lock settings and light settings. Occasionally, a software update can reset these to default or toggle things off. Make sure the feedback (lights flashing) is turned on.
When to Disconnect the Battery (The Hard Reset)
If you have tried everything above-the subscription is paid, the hood is closed, there's no check engine light, and you're holding the button correctly-the computer might just be glitched.
Computers freeze. Your phone freezes. Your car's computer can freeze too. You can force a reset by disconnecting the 12V battery.
Note: This will reset your radio stations and maybe your clock.
- Open the hood.
- Use a 10mm wrench to loosen the Negative (-) black cable on the battery.
- Pull the cable off the terminal.
- Wait about 10 to 15 minutes. This lets all the capacitors in the computer drain out.
- Put the cable back on and tighten it.
This forces the Remote Connect module to reboot. I've had friends do this on their Rav4s and Highlanders, and it clears up weird electrical gremlins immediately.
Summary of the Checklist
So, before you go spend $150 at the dealer for a "diagnostic fee," run through this list one last time:
- Sequence: Lock, Lock, Hold (3+ seconds).
- Subscription: Is your Remote Connect trial over?
- Doors/Hood: Open and slam them all shut.
- Hazards: Are the lights flashing when you press the buttons? If not, check the fob battery.
- Dashboard: Is the Check Engine Light on?
- Location: Is the car in a deep sleep or out of cell range?
Most of the time, it's the subscription or the hood latch. It's annoying, but usually, it's an easy fix.
Frequently Asked Questions
Does the 2021 Highlander have remote start on all trims?
Most trims have it, but not all. The XLE, Limited, and Platinum almost certainly have it. The base L or LE models might rely entirely on the Audio Plus subscription service or might not have the hardware installed. If you bought it used, check your VIN with a Toyota dealer to be sure.
Can I start my Highlander with the key fob without a subscription?
This is the controversial part. For the 2021 model year, Toyota stated that the key fob remote start (RF remote start) requires an active Remote Connect subscription. However, some users report it working without it on the Premium Audio package. If yours stopped working, the expired subscription is the most likely culprit.
How long does the car run on remote start?
It runs for 10 minutes. It will shut off automatically after that. You can extend it for another 10 minutes if you do the remote start sequence again while it's running, but it won't run for more than 20 minutes total.
Why does the engine shut off when I open the door?
This is a Toyota safety feature that drives everyone crazy. Yes, it is normal. As soon as you unlock and open the door, the engine kills. You have to get in and restart it with the Push-to-Start button. Toyota says this is to prevent theft so someone can't just jump in your running car and drive off, even though the key isn't there.
Will remote start work if my hazard lights are on?
Usually, no. The system uses the hazard lights to signal that the car has received the command. If the hazards are already flashing (like if you parked illegally for a minute), the system might get confused and block the start.